Influence of convection and aerosol pollution on ice cloud particle effective radius

Jiang, Jonathan H.; Su, Hui; Zhai, Chengxing; Massie, Steven T.; Schoeberl, M. R.; Colarco, Peter R.; Platnick, S.; Gu, Yu; Liou, Kuo‐Nan

doi:10.5194/acp-11-457-2011

Cited by 62 publications

(56 citation statements)

References 28 publications

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“…Morrison and Grabowski (2011) used a 2-D cloud resolving model (CRM) to show that convection may subtly weaken, yet cloud top height and anvil IWC may increase in polluted compared to clean conditions, resulting in a reduction of r ei by up to a factor of two. Simultaneous observations of r ei from MODIS and IWC from the Microwave Limb Sounder (MLS) suggest that more intense convection (defined by positive anomalies of IWC) increases r ei while polluted air (defined by positive anomalies of aerosol τ ) decreases r ei (Jiang et al, 2011). However, whether convection is dynamically invigorated by increased aerosol concentrations is highly debatable (Rosenfeld et al, 2008;Fan et al, 2013;Grabowski, 2015).…”

Section: Introductionmentioning

confidence: 99%

Ice cloud microphysical trends observed by the Atmospheric Infrared Sounder

et al. 2018

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Abstract. We use the Atmospheric Infrared Sounder (AIRS) version 6 ice cloud property and thermodynamic phase retrievals to quantify variability and 14-year trends in ice cloud frequency, ice cloud top temperature (T ci ), ice optical thickness (τ i ) and ice effective radius (r ei ). The trends in ice cloud properties are shown to be independent of trends in information content and χ 2 . Statistically significant decreases in ice frequency, τ i , and ice water path (IWP) are found in the SH and NH extratropics, but trends are of much smaller magnitude and statistically insignificant in the tropics. However, statistically significant increases in r ei are found in all three latitude bands. Perturbation experiments consistent with estimates of AIRS radiometric stability fall significantly short of explaining the observed trends in ice properties, averaging kernels, and χ 2 trends. Values of r ei are larger at the tops of opaque clouds and exhibit dependence on surface wind speed, column water vapour (CWV) and surface temperature (T sfc ) with changes up to 4-5 µm but are only 1.9 % of all ice clouds. Non-opaque clouds exhibit a much smaller change in r ei with respect to CWV and T sfc . Comparisons between DARDAR and AIRS suggest that r ei is smallest for singlelayer cirrus, larger for cirrus above weak convection, and largest for cirrus above strong convection at the same cloud top temperature. This behaviour is consistent with enhanced particle growth from radiative cooling above convection or large particle lofting from strong convection.

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Section: Introductionmentioning

confidence: 99%

Ice cloud microphysical trends observed by the Atmospheric Infrared Sounder

et al. 2018

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“…In this study, a prescribed D e with a value of 85 µm based on available ice crystal sizes determined from six observational campaigns reported by Fu (1996) was used in the clean conditions of off-line studies. Note that the D e -IWC-AOD relationships (Jiang et al, 2011) have been derived from the climatological satellite data and are the same throughout the year. Their seasonal variation and its impact on climate simulations will require further analysis.…”

Section: Parameterization Of Aerosol First Indirect Effect On Ice Cloudmentioning

confidence: 99%

“…Using least-squares fitting to the observed data, an analytical formula to describe the variation in D e with IWC and AOD for several regions with distinct characteristics of D e -IWC-AOD relationships has been obtained (Jiang et al, 2011). Because IWC is directly related to convective strength and AOD represents aerosol loading, this empirical formula provides a means of quantifying the relative role of dynamics and aerosols in controlling D e in different geographical regions, and at the same time of establishing a framework for parameterization of aerosol effects on D e in climate models.…”

Section: Aerosolsmentioning

confidence: 99%

“…For the aerosol effect on D e , we follow the approach presented by Jiang et al (2011), in which an analytical formula was obtained to describe the variations of D e with IWC and AOD for several regions with distinct characteristics of D e -IWC-AOD. Using MLS IWC measurements at 215 hPa to indicate convective strength (CONV) and AOD measurements from MODIS to denote aerosol loading, as well as using a least-squares fitting, an empirical formula for ice cloud effective radius r e (D e /2) as a function of CONV and AOD was derived to approximately capture the observed relationships among these three parameters as follows: Note that this D e -IWC-AOD relation only works for AOD larger than 0.…”

Section: Parameterization Of Aerosol First Indirect Effect On Ice Cloudmentioning

confidence: 99%

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Dust aerosol impact on North Africa climate: a GCM investigation of aerosol-cloud-radiation interactions using A-Train satellite data

Gu¹,

Liou²,

Jiang

et al. 2012

Atmos. Chem. Phys.

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Abstract. The climatic effects of dust aerosols in North Africa have been investigated using the atmospheric general circulation model (AGCM) developed at the University of California, Los Angeles (UCLA). The model includes an efficient and physically based radiation parameterization scheme developed specifically for application to clouds and aerosols. Parameterization of the effective ice particle size in association with the aerosol first indirect effect based on ice cloud and aerosol data retrieved from A-Train satellite observations have been employed in climate model simulations. Offline simulations reveal that the direct solar, IR, and net forcings by dust aerosols at the top of the atmosphere (TOA) generally increase with increasing aerosol optical depth. When the dust semi-direct effect is included with the presence of ice clouds, positive IR radiative forcing is enhanced since ice clouds trap substantial IR radiation, while the positive solar forcing with dust aerosols alone has been changed to negative values due to the strong reflection of solar radiation by clouds, indicating that cloud forcing associated with aerosol semi-direct effect could exceed direct aerosol forcing. With the aerosol first indirect effect, the net cloud forcing is generally reduced in the case for an ice water path (IWP) larger than 20 g m −2 . The magnitude of the reduction increases with IWP.AGCM simulations show that the reduced ice crystal mean effective size due to the aerosol first indirect effect results in less OLR and net solar flux at TOA over the cloudy area of the North Africa region because ice clouds with smaller size trap more IR radiation and reflect more solar radiation. The precipitation in the same area, however, increases due to the aerosol indirect effect on ice clouds, corresponding to the enhanced convection as indicated by reduced OLR. Adding the aerosol direct effect into the model simulation reduces the precipitation in the normal rainfall band over North Africa, where precipitation is shifted to the south and the northeast produced by the absorption of sunlight and the subsequent heating of the air column by dust particles. As a result, rainfall is drawn further inland to the northeast.This study represents the first attempt to quantify the climate impact of the aerosol indirect effect using a GCM in connection with A-Train satellite data. The parameterization for the aerosol first indirect effect developed in this study can be readily employed for application to other GCMs.

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“…The COF's show clear variability at higher altitudes (10-16 km), i.e., the COF is observed to be higher in 2008 than in 2009 during monsoon months as seen in Fig. 4(b) and d. It is inferred from the vertical distribution of aerosols and clouds that with increased convection more aerosols are advected to higher levels (Jiang et al, 2007(Jiang et al, , 2011. Thus, high AOF's were persistent in 2008 than in 2009 at higher levels, suggesting that increased convection vertically transported more aerosols in 2008.…”

Section: Precipitation Variabilitymentioning

confidence: 71%

Aerosol-Cloud-Interaction Variability Induced by Atmospheric Brown Clouds during the 2009 Indian Summer Monsoon Drought

Bhawar

Rahul

2013

Aerosol Air Qual. Res.

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Contrasting monsoons of 2008 and 2009 provided a test bed to enhance the understanding of the aerosol variability and aerosol-cloud interaction. Vertical aerosol profiles derived from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) are used to delineate the aerosol properties during the two contrasting Indian summer monsoons. We observed a 30-40% increase in the aerosol occurrence frequency (AOF) in lower altitudes (below 6 km) in 2009 and a 5-8% enhancement in AOF at higher altitudes in 2008. The cloud occurrence frequency also showed more deep convective clouds in 2008 (13-15%) than in 2009. Cloud Fraction, Aerosol Optical Depth and TRMM precipitation data sets have been also used to investigate the aerosol-cloud interaction. We define the microphysical effect as the increase in cloud fraction with increase in aerosols (CCN) and the radiative effect as the decrease of cloud fraction with increase in aerosol loading. We observe a stronger microphysical effect than the radiative effect in 2008 as compared to 2009. In 2009, atmospheric brown clouds were observed from March to September, which slowed down the microphysical effect and enhanced the radiative effect. This resulted in a 30% reduction in the total cloud fraction that may have reduced precipitation, and invigorated the drought conditions during 2009.

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Influence of convection and aerosol pollution on ice cloud particle effective radius

Cited by 62 publications

References 28 publications

Ice cloud microphysical trends observed by the Atmospheric Infrared Sounder

Ice cloud microphysical trends observed by the Atmospheric Infrared Sounder

Dust aerosol impact on North Africa climate: a GCM investigation of aerosol-cloud-radiation interactions using A-Train satellite data

Aerosol-Cloud-Interaction Variability Induced by Atmospheric Brown Clouds during the 2009 Indian Summer Monsoon Drought

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